[Public-List] Propeller Shaft Material

[Don Lang]

Aquamet shafts ftw!  :-)
They cost more but are superior.
We have only seen one fail, but to be fair, that was on a 97 footer we built with a three inch shaft and they were  pushing hard off the west coast and really loading her up in big seas. The loss of the $7,000 prop on the end really hurt our feelings as she was still under warranty.

If you go with stainless try and ensure the vessel has good water flow around the shaft when the boat is not being used. Pitting and corrosion due to lack of oxygen can be a real problem. many mistake it for galvanic corrosion.

Here's a good material comparison site http://www.machinist-materials.com/stainless_table.htm

>From the Bertram31.com site:

 Basic shaft characteristics: 
>Standard 303 or 304 stainless steel shafting:  Approx. 100,000 P.S.I.
>(Good economy shafts)
> Figure on replacing every few years...
>
>>Aquamet 19 stainless alloy shafting:  Approx. 140,000 P.S.I.
>(High strength, but more flexibility than A22 - Far superior to 303 or 304)
>
>
>>Aquamet 22 stainless alloy shafting:  Approx. 145,000 P.S.I.
>(Higher strength, but more brittle than A19 - Most preferred shaft material)
>
>
>>Monel 400 series shafting:  up to 150,000 P.S.I.(Good
>shaft material for strength and corrosion resistance, but not as tough
>as Aquamet, tendency to twist off under extreme loading conditions)
>
>Cheers, Don
>


      
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